I have an 1971 75.hp mercury thunderbolt motor. Which now has no spark.
History:
when purchased it was not running, all the wire insulation was disintegrated. Rewired with automotive grade 12awg wire. Crimped and soldered all connectors. Once everything was rewired, i could get it to run but only in forward gear and throttled WOT. But would only run for 5-10 sec. So i thought either timing issue, carburetor or fuel pump. Rebuilt fuel pump, put new float, needle and seat in carb. Replaced all gas line. Downloaded service manual and set the points gap to .020 and set timing. Tried starting it again, this time i couldnt get it to do anything. Checked spark, had spark on both cylinders. Plugs were wet so i know i was getting fuel. Emptied fuel tank and replaced gas with brand new gas with proper mixture. Still no start. I was running Autolite 2872 plugs and changed them to Champion L76V thinking maybe it didnt like the Autolites. No change, still had spark but no start. After all the pulling i got tired of that and started using a drill with a 5/8 socket to spin motor. Then hooked up a gap tester, set it to somewhere around 1/4" to 3/8" gap and it was firing. As i was doing that the spark quit and i couldn't get it to spark again. After doing some troubleshooting i determined it was probably the stator. Ordered a used stator off ebay. OHM'd the old stator versus the new, got 7 megaohms on the old one and 11 megaohms off the new one. Bought new coils, which now ohming them against the old ones, i dont think they were bad. All 4 coils, 2 old and 2 new, measure 0.9 ohms between +- posts and 596 ohms tower to ground pigtail.
What doesn't make sense to me is when I check continuity at the points, with both points open, i get continuity between both points. Not between the adjustable side, between the the ones the attach the the insulator blocks.
Right now I am at a standstill and don't know what else to troubleshoot. I have heard of people switching to the phelon ignition system on these but i have put more money in this than i want right now.
Sooooo..... go ahead and start asking questions
History:
when purchased it was not running, all the wire insulation was disintegrated. Rewired with automotive grade 12awg wire. Crimped and soldered all connectors. Once everything was rewired, i could get it to run but only in forward gear and throttled WOT. But would only run for 5-10 sec. So i thought either timing issue, carburetor or fuel pump. Rebuilt fuel pump, put new float, needle and seat in carb. Replaced all gas line. Downloaded service manual and set the points gap to .020 and set timing. Tried starting it again, this time i couldnt get it to do anything. Checked spark, had spark on both cylinders. Plugs were wet so i know i was getting fuel. Emptied fuel tank and replaced gas with brand new gas with proper mixture. Still no start. I was running Autolite 2872 plugs and changed them to Champion L76V thinking maybe it didnt like the Autolites. No change, still had spark but no start. After all the pulling i got tired of that and started using a drill with a 5/8 socket to spin motor. Then hooked up a gap tester, set it to somewhere around 1/4" to 3/8" gap and it was firing. As i was doing that the spark quit and i couldn't get it to spark again. After doing some troubleshooting i determined it was probably the stator. Ordered a used stator off ebay. OHM'd the old stator versus the new, got 7 megaohms on the old one and 11 megaohms off the new one. Bought new coils, which now ohming them against the old ones, i dont think they were bad. All 4 coils, 2 old and 2 new, measure 0.9 ohms between +- posts and 596 ohms tower to ground pigtail.
What doesn't make sense to me is when I check continuity at the points, with both points open, i get continuity between both points. Not between the adjustable side, between the the ones the attach the the insulator blocks.
Right now I am at a standstill and don't know what else to troubleshoot. I have heard of people switching to the phelon ignition system on these but i have put more money in this than i want right now.
Sooooo..... go ahead and start asking questions
